Ryuzaki Ikuo

Ikuo Ryuzaki witnessed murder of his sensei 15 years prior to the beginning of manga. As the incident was covered up he swore along with his childhood friend Tatsuya to find the culprit behind his senseis death and bring him to justice. Nowdays 15 years after the incident and senseis death Ikuo Ryuzaki is an sergeant in 2nd Division of Police department.